The resistivity of electrical components is an important property. In the electronics field, precise knowledge of the resistivity of various materials or components is often critical to the determination of whether and how the materials or components will be used.
Conventional resistivity measurement techniques involve the placement of two electrical probes on the component to be measured. The probes are generally connected by an ammeter or other measuring device that measures the current traveling through the material between the probes This measurement of current flow I, resulting from the application of a known voltage V, is used to determine the resistivity of the component according to the well-known formula R=V/I.
An essential feature of conventional measurement techniques is thus contact between the probes and the material that is being measured. In many situations, such contact is undesirable.
For example, in the microelectronics area, it is often necessary to measure the resistivity of metal lines that have been deposited on substrates. These metal lines are used for connecting circuits in personal computer boards and multichip modules, among other uses. In order to measure the resistivity of the metal lines using conventional techniques, it is necessary to contact the probes with the line. If the metal line is not very firmly attached to the substrate, and often even if it is, the probe may scratch away the metal or otherwise damage the metal line. Scratches and other forms of damage to a metal line may interfere with the electrical connection provided by the metal line. This produces undesirable performance of the component on which the line is deposited. If the damage from the probe is severe enough, the metal line may have to be redeposited.
A measurement system capable of providing a good resistivity measurement for electrical components, such as metal lines on a substrate, or other materials, without damaging the components or materials, is desirable.